Media outlets around the world seized on the tweets, calling Persson depressed. The billionaire again took to Twitter on Monday morning to defend his comments, saying, "fwiw, while there are articles about my depression because I had a bad day and vented on a trend I saw, I'm sitting here having a nice day."

Regardless of whether his tweets were momentary venting or a sign of deeper malaise, Persson's comments reflect some of the lesser-known downsides of a massive windfall, or "sudden wealth syndrome."

This has been known to occur among founders who sell their companies (Microsoft acquired Minecraft last year).

Entrepreneurs who are naturally driven to create, build, innovate and work around-the-clock realize their dream upon selling their company. But once they do, they sometimes find themselves flush with cash but deficient in purpose.

What's more, being rich allows someone to disengage from the hoi polloi and live in peace on the top of the mountain. But that peace can also be isolating.

Add to that the distrust that can come with being rich—as some assume everybody wants something from them—and being rich can quickly become its own form of prison.

Though many will not take pity on others' riches, Persson's comments offer an important lesson: When it comes to large wealth, be careful what you wish for.